Australian Energy Market Operator

AEMO operates Australia's National Electricity Market (NEM), the interconnected power system in Australia’s eastern and south-eastern seaboard, and the Wholesale Electricity Market (WEM) and power system in Western Australia.

AEMO operates gas retail markets in New South Wales and the Australian Capital Territory, Queensland, South Australia, Victoria, and Western Australia. AEMO also operates wholesale gas markets in south-eastern Australia, those being the Declared Wholesale Gas Market in Victoria (DWGM), the Short Term Trading Market in Adelaide, Brisbane and Sydney (STTM), and the Gas Supply Hub (GSH), whose trading locations are based at Wallumbilla in Queensland, and Moomba in South Australia. AEMO also operates the Natural Gas Services Bulletin Board (GBB), and is system operator of the Victorian Gas Declared Transmission System. AEMO is also responsible for Gas Services Information functions in Western Australia.

The following impacts are expected during the maintenacne period:- All access to the Declared Wholesale Gas Market Production Systems will be unavailable.- All access to the MIBB for the NSW/ACT Retail Gas Market Participants will be unavailable.

Support Information:Report any impacts to the AEMO Information and Support Hub or on External 1300 236 600.

6291723 May 2018 10:35GENERAL NOTICE

Planned frequency tests in Tasmania on 23/05/2018

AEMO ELECTRICITY MARKET NOTICEFrequency tests in Tasmania have been arranged between AEMO and relevant participants.Testing involves making selective changes to AEMO's AGC control system, and to some of generating units' governors controls in Tasmania to measure the effect on Tasmanian frequency control under normal operating conditions.Scheduled time of the test is between 1100 hrs - 1500 hrs on 23/05/2018Market Participants in mainland regions will not be affected by the tests.

Manager NEM Real Time Operations

6291423 May 2018 4:18GENERAL NOTICE

Possible intervention to manage power system security in South Australia (SA) Region

AEMO ELECTRICITY MARKET NOTICE

The synchronous generating units expected to be synchronised in SA from 0030 hrs 24/05/18 in Pre-dispatch published at 0400 hrs 23/05/18 are inadequate to maintain sufficient system strength in SA and hence a secure operating state.

AEMO currently estimates that, in the absence of sufficient market response by 2230 hrs 23/05/18, AEMO may need to intervene by issuing a direction requiring one or more SA synchronous generating unit(s) to operate or remain synchronised from 0030 hrs 24/05/18, to maintain power system security in SA.

Possible intervention to manage power system security in South Australia (SA) Region

AEMO ELECTRICITY MARKET NOTICE

The synchronous generating units expected to be synchronised in SA from 0030 hrs 24/05/18 in Pre-dispatch published at 1300 hrs 22/05/18 are inadequate to maintain sufficient system strength in SA and hence a secure operating state.

AEMO currently estimates that, in the absence of sufficient market response by 1700 hrs 22/05/18, AEMO may need to intervene by issuing a direction requiring one or more SA synchronous generating unit(s) to operate or remain synchronised from 0030 hrs 24/05/18 , to maintain power system security in SA.

Manager NEM Real Time Operations

6290622 May 2018 16:55CONSTRAINTS

Updated generator combinations for SA system strength

AEMO MARKET NOTICE

Updated generator combinations for SA system strength

AEMO is continuing to investigate system strength requirements in South Australia.

Through this work, AEMO has identified two additional generator combination which meet minimum system strength requirements in South Australia.

For more information refer to the updated limits advice:https://www.aemo.com.au/-/media/Files/Electricity/NEM/Security_and_Reliability/Congestion-Information/2018/Transfer-Limit-Advice---South-Australian-System-Strength.pdf

A further update to this advice is planned before the end of June 2018.